We (my son and I) have been having good results using 4.2 gr. of W-231 with Berry's 124 gr. RN plated bullets. At my club range this combo works well in his Glock 19 (gen. 3) and my P-38. Incidentally, 5 gr. of this same powder works great in my son's FNP-40 (with Berry's 180 gr. RNFP plated bullets) and in my M1911 clone (with Berry's 230 gr. RN plated bullets). We had started out using Unique in all the guns mentioned and it worked okay. However, a couple guys at the club suggested trying W-231. I got a can and tried it. It's cleaning burning than Unique & meters the most consistently through my powder measure of anything I've used. The accuracy has been as good or better too. From here on out I'm going to save my Unique for shotshells.